Employee Benefit Plans - Summary of Weighted-Average Assumptions Used to Determine Net Benefit Obligation (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.30%	5.20%	5.70%
Long-term return on plan assets	9.20%	9.30%	9.20%